The present invention relates generally to hydrogen leak detection systems and surface spectroscopic processes, and more particularly, to a system and method of detecting and monitoring hydrogen contamination of palladium surfaces and utilizing information contained therein for hydrogen sensor evaluation.
Detecting leakage of gaseous hydrogen (GH2) in hydrogen-fueled vehicles is critical in preventing generation or accumulation of flammable and explosive concentrations. Concentrations of GH2 that are greater than or equal to approximately 4% in air are flammable and can be explosive. GH2 leakage detection is also desired for emerging hydrogen fuel-celled infrastructures.
In hydrogen-fueled launch vehicles, during cryogenic storage and subsequent transport of liquid hydrogen, leaks typically occur and are associated with sealed connections. To detect the leaks mass spectrometers are typically utilized. Mass spectrometers have sufficient chemical specificity detection capability to allow detection of leaking amounts of GH2 as opposed to detection of other atmospheric contaminants, such as carbon disulfide, carbon monoxide, and methane that exist in an operating environment.
However, mass spectrometers have unacceptably slow response time in detection of leaking GH2 when applied to large vehicles, such as rockets and the like. Palladium based sensors, on the other hand, have a relatively quick response time in detection of GH2. Multiple palladium sensors are based on reversible changes in the physical properties of palladium in the presence of GH2 or are based on use of palladium as a catalyst for reversible chemical reactions in detection of GH2.
Unfortunately, palladium sensors lack the chemical specificity capability required for deciphering between GH2 and other atmospheric contaminants. Also, the palladium sensors, due to being chemically affected or xe2x80x9cpoisonedxe2x80x9d by multiple contaminants, have a limited service life. It can be difficult to determine when the service life is up and when a palladium sensor needs to be repaired or replaced.
A couple of techniques have been suggested to overcome the disadvantages associated with palladium sensors. One technique is the use of thin films over surfaces of the palladium sensors that only allow passage of GH2 as opposed to the other atmospheric contaminants. The use of thin films although preventing clogging of the palladium surfaces increases complexity of a sensor system, reduces GH2 detection response time, and causes a sensor to become application specific.
Another technique is to heat resistive portions of the palladium sensors to desorb contaminants and extend service life of the sensors. In heating the sensors, temperature changes are monitored to detect amounts of GH2. Temperature changes are different for GH2 contamination versus other contamination. In order to heat the, resistive portions system and operational complexity is increased. Additionally, there is a significant amount of ambiguity in monitoring the temperature changes, which can cause incorrect GH2 contamination determination.
It is therefore desirable to provide a GH2 contamination detection system that has sufficient chemical specificity capability, has a relatively quick GH2 detection response time, and is capable of determining when a sensor is operating inappropriately and needs to be repaired, recalibrated, or replaced.
The present invention provides a system and method of detecting and monitoring hydrogen contamination of palladium surfaces and utilizing information contained therein for hydrogen sensor evaluation. A hydrogen detection system is provided and includes a hydrogen sensor that detects contamination within a reaction member and generates a hydrogen contamination signal. A surface spectroscopic system is operational in conjunction with the hydrogen sensor and determines contamination of the hydrogen sensor and generates a sensor contamination signal. A controller is electrically coupled to the hydrogen sensor and the surface spectroscopic system and compares the hydrogen contamination signal to the sensor contamination signal and generates a corrected hydrogen contamination signal.
The present invention has several advantages over existing hydrogen detection sensors. One advantage is that it provides accurate chemical specificity capability and at the same time provides relatively quick GH2 detection response time.
Another advantage of the present invention is that it provides a system for evaluating performance of a hydrogen sensor so as to determine when to repair, recalibrate, or replace the hydrogen sensor.
Furthermore, the present invention provides a hydrogen detection and evaluation system that is not application specific in that it is easily configured for multiple applications.